It's time to put your snow blower away for the season. Chances are you've already stuck it in the corner of your garage or shed and happily forgot about it but, trust me, drag it outside and take a little time to prep it for proper storage.
Beside, it's a lot easier to work on it in the natural sunlight of your driveway or back yard than in the thick of a major Winter snow storm. It will not take long at all if you have been taking good care of it. First of all, buy yourself a spark plug, some Winter weight oil such as 5W 20 or 5W30, the same year round oil that most cars use these days. Also, buy some fuel preservative such as Sta-Bi, Store Safe or any other comparable brand.
First off, change the spark plug even though it looks good. It's worth the few bucks for the added benefit of a hot spark on a cold day. It would not hurt to snug down the head bolts in case any of them have become loose. If you do not have a torque wrench, just snug them down while choking up on the wrench handle so as not to over-due it. Use a criss-cross pattern for even distribution.
Chances are the bolts will not even move but it's worth the extra 2 minutes. Top off the gas tank with fresh fuel, leaving enough room for the gas conservative recommendations and start the snow blower up and let it run for 10 minutes or so in order for the conservative to make it's way into the carburetor and it's small orifices and cavities where un-attended fuel turns to varnish and creates a no-start situation come the first snow fall.
Note: There is another school of thought that says to drain the fuel tank and run the carburetor completely out of fuel for storage. In my opinion, flip a coin and do whatever you want. They both prevent the problem of stale fuel plugging up your carburetor.
Next, take advantage of the warm engine to drain the hot engine oil while the nasty sediments are properly suspended and drain out with the old oil instead of staying behind in the bottom of the oil pan. Dispose of the oil properly at your local auto repair shop.
If you're up to it, replace any worn or stretched drive belts and rubber faced drive disc if your snow blower has one. Otherwise, save that for your local servicing dealer. Lubricate all external pivot points on the levers, cables, linkage, etc. with some WD-40, white lithium grease or an appropriate substitute. All those small pivot holes dry out and become elongated over time if they are never lubricated.
That's it. Enjoy your summer!